Bursting disc assembly retaining ring with a clover leaf cutting pattern and projection

ABSTRACT

In combination with a rupture disc assembly, there is provided an improvement by using a support ring having a projection and a continuous, generally clover leaf pattern cutting edge.

FIELD OF THE INVENTION

[0001] This invention relates to a pressure relief valve, and moreparticularly to a pressure relief valve being of a metal rupture disc inthe form of thin rupture members having a metal liner body with aweakened portion including, in the form of a scored pattern, where themetal liner is placed in juxtaposition with a bursting disc.

BACKGROUND OF THE INVENTION

[0002] The present invention relates to safety pressure relief devicesand, in particular, to rupture disc assemblies, including reversebuckling rupture discs, and also to methods of manufacturing suchrupture discs and assemblies.

[0003] Rupture discs have been known in this art for many years.Normally, the rupture discs arc manufactured to have a rupturablemembrane to provide a safety mechanism to relieve excessive pressurewithin an over-pressurized system or vessel. The rupture disc and orrupture disc assemblies are typically placed within such a system orvessel so as to prevent the flow of a liquid or a gas through such adevice until the rupture disc ruptures through excessive orover-pressure loads. Typically, rupture discs have a score patternformed by cuts, machined or by other conventional methods into the domeportion of the disc to enable the disc to buckle and to burst when underexcessive pressure.

[0004] Rupture discs having support rings providing cutting projectionshave been used, but are restricted in use, being capable of use withgases only and sometimes restricted in pressure range.

[0005] Obviously, if a rupture disc assembly could be developed whichhad better operating characteristics, including the ability to be usedwithin a gas and or liquid environment capable of low and or high burstpressures, all without reducing the economic viability of Such discs,there could be a wider application for the use of rupture discsassemblies.

SUMMARY OF THE INVENTION

[0006] With the present invention, it has been found that by providing arupture disc assembly having a support ring including a projection and apredetermined configuration for the continuous score line, incombination with a rupture disc, the disadvantages of using standardrupture discs with conventional support rings are overcome cost-wise andthe combination of the present invention permits a wider range ofapplication for varying liquid and gas usages, and varying burstpressures.

[0007] The present invention provides a rupture disc combination whichpermits the use of rupture disc members in association with a certaintype of rupture disc assemblies which overcomes the disadvantages withrupture discs assemblies per se, and yet provides the advantages ofcertain features of known rupture discs.

[0008] It is therefore one aspect of the invention to provide in arupture disc assembly having a support ring adapted to support arupturable rupture disc member; said support ring including an aperture,an upper and lower surface and a continuous side surface, theimprovement wherein the support ring includes contiguous cutting meansabout the inner peripheral wall, the cutting means comprising aplurality of adjacent arcuately contoured cutting means having aninnermost surface of the arcuate contour spaced at a closer distance tosaid inner peripheral wall than outer ends of the arcuate contour.

[0009] In another aspect of the present invention there is provided in arupture disc assembly having a support ring adapted to support arupturable rupture disc member; the support ring including an aperture,an upper and lower surface and a continuous side surface, theimprovement wherein the support ring includes engaging means forengaging a ruptured disc after rupture of the same, the engaging meanscomprising a projection extending upwardly from one of the surfaces ofthe support ring and extending inwardly of the surface over the apertureto thereby engage a displaced ruptured disc.

[0010] In another aspect of the present invention there is provided in arupture disc assembly having a support ring adapted to support arupturable rupture disc member; the support ring including an aperture,an upper and lower surface and a continuous side surface, theimprovement wherein the support ring includes a contiguous cuttingsurface operatively associated with said projection, the cutting surfacepositioned on said inner peripheral portion on the support ring, theprojection of the cutting surface having a generally clover-leafconfiguration.

[0011] In various alternative embodiments, the device according to anyof the above aspect, the disc further includes a dome having apre-determined transition radius between the dome and the support ring.

[0012] In various alternative embodiments, the support ring includes atransition radius substantially corresponding to that of the disc.

[0013] In alternative versions, the support ring transition radiusincludes a diameter of the transition radius being smaller than thetransition radius of the disc.

[0014] Desirably, in accordance with the present invention, there isprovided in a rupture disc having a rupturable rupture member togetherwith a support system including a support ring associated with therupture disc, the support ring having a projection formed within thering adapted to retain post burst disc material, the improvement whereinthe rupture disc supporting ring comprises a predetermined continuousscore line therein adapted to cut the rupture disc when the disc bucklesat a predetermined pressure, the support ring with the continuous cut orscore line being in operative association with the projection formed inthe support ring.

[0015] It is therefore another aspect of the present invention toprovide a bursting disc in combination with a support ring having aprojection formed on one side of the ring in combination with acontinuous score pattern is of a generally clover-leaf configuration.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016]FIG. 1 is an exploded cross-sectional view of a bursting discassembly.

[0017]FIG. 2 is a top view of a rupture disc.

[0018]FIG. 3 is a top view of a support ring.

[0019]FIG. 4 is a cross-section view of the disc and support ringillustrating the transition diameter,

[0020]FIG. 5 is a enlarged view of the portion in circle A of FIG. 4.

[0021]FIG. 6 is a top view of the lower holder,

[0022]FIG. 7 is a view of the upper holder viewed from below,

[0023]FIG. 8 is a side view of the assembled device.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0024] For purposes of description herein the terms upper, lower,vertical and horizontal along with other directional references shall berelative to the invention as oriented in FIGS. 1 and 5, as illustratedin a pressure to non-pressure flow direction. It should also beunderstood that the various disclosed embodiments are merely exemplaryand are utilized in a manner as would be readily understood by a personin the art.

[0025] The assembly as generally indicated by reference numeral 10,designates a rupture disc assembly including, in a pressure tonon-pressure direction sequential relationship, a lower support holderor flange 20, a rupture disc 50, a support ring 100 and an upper supportholder or flange 60. The assembly 10 when in use is securely held in anassembled condition through any conventional means, such as through theuse of bolts or other mounting arrangements. The support structure 100includes a projection or tongue member 120 formed in one side of thering 100, and a continuous cutting surface 130 formed in the remainingnon-projection sides of the ring (see FIG. 3).

[0026] The assembly 10 may be positioned within a safety releasestructure (not shown), such as a vent or pressure release valveassembly, and is normally adapted to prevent the flow of a liquid or agas, in high and/or low pressures, through the assembly under a normalor predetermined burst pressure. The disc 50 is adapted to rupture orprovide relief for excessive pressure when the predetermined maximumburst pressure of a bursting disc is exceeded.

[0027] When viewed from a pressure side to the non-pressure side of thedevice 10, there is provided a lower support holder or flange 20, whichis positioned adjacent the lower surface of a bursting disc 50. Thelower support holder or flange 20 may be constructed of any suitablematerial known in the art. The support holder or flange 20 in use isadapted to provide a secure seal against leakage between the disc 50 andthe portion of the pressure vessel into which the assembly 10 is placed.

[0028] As illustrated in FIG. 6, the lower support holder or flange 20is of a generally circular or ring configuration, having a centralizedaperture or bore 22, an inner peripheral wall 24 and an outercircumferential wall 26, a lower surface 25 (FIG. 1) and an upperannular surface or inner seating surface 40 around the centralizedaperture 22 of the flange 20. In a preferred embodiment, the outer wallportion 26 of the lower holder or flange 20 extends above and around theannular surface 40, having a generally extending peripheral outer rimportion 28. Formed within the surface 40, through any conventional meanssuch as milling, die forming, tooling or the like, is a circumferentialraised projection or member 42, spaced inwardly of the outer rim wall28. Raised member or projection 42 is adapted to provide a protuberanceagainst which disc 50 abuts. When the assembly 10 is in a fullyassembled condition, the raised projection or member 43 is adapted tosecurely retain the disc 50 against the support ring 110 and the supportholder 20. As the assembly 10 is assembled and secured throughconventional means, the pressure between the flange portion of the discand the raised projection or member 42 allows for the flange portion toform or bend onto the projection thereby providing a seal and retainingthe disc 50 in place.

[0029] In a preferred embodiment, the outer rim 28 is interrupted andprovided with a gap portion or interruption 30. Most preferably the gapportion 30 is provided or interrupted by a segment 32 of the outer rimor wall portion, wherein the segment or segments are adapted to match orfit with a corresponding or mating portion on a subsequent element ofthe assembly. In a preferred embodiment, the raised projection or member32 is spaced midway between the outer rim and the inner ring wall 24.

[0030] As illustrated in FIGS. 1 and 3, the support ring 100 handleportion 120. The support ring 100 is of a generally circularconfiguration, having an upper surface 111 and a lower surface 12, thering being adapted through dimension and position to fit snugly withinthe assembly 10 as shown in FIGS. 1, 4 and 5. The support ring 100further includes a central aperture 115, corresponding to that of thedisc and flanges 20 and 60. The support ring has an inner peripheraledge 116 and an outer circumferential edge 117. The inner peripheraledge 116 includes a projection or hinge member 120, a series of downwardprojections 110, and an opening pattern or cutting edge 130 extendeither side of the projections 110. The projection or hinge member 120is formed at a predetermined point along the inner ring surface, theremaining portion providing the opening pattern or cutting edge 130. Thecutting edge 130 has a generally continuous configuration, whichaccording to the present embodiment is of a generally clover leafpattern.

[0031] As shown in FIG. 1, the projections 110 and the cutting edge 130,and projections 110 of the support ring 100, when viewed from a pressureside to a non-pressure side perspective, depend or otherwise extenddownwardly below the horizontal axis of the supporting ring 100. Asshown in an assembled state, the cutting edge 130 and projection 120depend into the concavity of the dome portion of the disc 50, whereinthe transition radius and diameter is substantially similar to that ofthe disc. The support ring 100, including inner peripheral edge 125 andouter peripheral edge 126, has a predetermined transition radius andtransition diameter, discussed in detail below.

[0032] The opening pattern or cutting edge 130 in the example shown inFIG. 2, is of a generally clover leaf configuration, extendingcontinuously along an inner peripheral portion 116 of the supportingring 100 Most desirably, the cutting member 130 having a generallyclover leaf configuration depends from the horizontal plane of thesupport ring 100 towards and within the dome portion of the disc 50. Thecutting edge 130 includes the tear initiation points 110, and arcuatelycurved continuous cutting portions 134, the cutting edge has an anglegenerally being between 50 and 70 degrees, and most desirably about 60degrees. The arcuately curved cutting portions 134 include inner arcswhich substantially coincide with the bore of an upper support holder60.

[0033] This provides for a non-fragmenting burst pattern of the disc,although other suitable angles may be used. A method of forming thiscutting pattern is described in further detail below.

[0034] As shown in FIG. 3, the outer circumferential edge of the supportring 100 includes the projection 120. Formed within the projection 120through any conventional means is a slot or aperture 106, adapted to aidin the proper assembling of the assembly 10 by being able to receivemember 32, on the lower holding member 20.

[0035] As illustrated in FIGS. 1 and 2, the disc 50 is of a conventionaltype commonly referred to as a reverse buckling disc, fabricated from aconventional metal material such as steel, steel alloy or other, and isadapted to tear upon reversing along the predetermined cutting pattern130 on the support ring 110 when a pressure load exceeds thepredetermined pressure load of the rupture disc 50. The rupture disc 50includes a central portion or dome portion 52, and a flange or rimportion 54, and is adapted to be positioned with the dome 52 facing in apressure flow direction between the support structure 100 and the lowerflange 20. Disc 50, when in use and under excessive pressure, is adaptedto reverse buckle towards the support ring 110 and the projection member120. The dome portion 52 of the disc 50 is cut or otherwise openedagainst the clover leaf pattern immediately after which the burst orbuckled disc is wrapped around the projection 120.

[0036] Disc 50 may be of any conventional type, such as a non-scoredreverse bursting disc. When utilized in accordance with the presentinvention, no score lines are required as the support ring 110 asdescribed in detail below includes a cutting formation which providesfor the serration and non-fragmentation of the disc 50. According to apreferred embodiment, when using a non-scored reverse buckling disc, thepresent invention is able to be utilized within both gaseous and liquidenvironments, and for both high and low burst pressures in both gaseousand liquid environments.

[0037] Most preferably, the disc 50 includes a transition region 45having a predetermined transition radius and diameter. The transitionradius between the dome portion of the rupture disc and the peripheralportion is approximately identical in both the rupture disc and thesupport ring. Desirably, the diameter of the transition radius of thesupport ring is approximately 0.010″ to 0.020″ smaller than thetransition radius of the disc.

[0038] As illustrated in FIGS. 4 and 5, the transition diameter andradius of the support ring and the disc, as indicated above, aresubstantially similar, with the support ring being adapted throughdimension and position to coincide with the disc 50. The transitiondiameter of the support ring 110, as generally indicated by referencenumeral 90, has a predetermined diameter and radius corresponding tothat of disc 50. This ratios of course will vary depending upon the sizeand diameter of the disc being used, as will be understood by oneskilled in the art.

[0039] A second upper holder or flange 60 is positioned abutting thesupport ring 100, as shown in FIGS. 1 and 8, on the non-pressure side ofthe disc 50. The upper support holder or flange 60 is adapted to providea secure seal against leakage between the non-burst disc 50 and thenon-pressure side of the assembly 10 when placed within a pressurevessel. The upper support holder 60 is similar to that of the lowersupport holder or flange 20, wherein the upper or non-pressure sidesupport holder or flange 60 has a generally cylindrical configurationincluding a central aperture 62, having a defined bore dimension, acontinuous side wall 64 and upper and lower surfaces 66 and 68,respectively. The upper support holder 60 includes a corresponding ormating portion 70 having a circumferential or annular seat to that ofthe outer rim of flange 20. Alternatively, the mating portion 70 of theupper support holder 60 is interrupted by spaced apart projections 74and 76, extending from the side wall 64. Projections 74 and 76 aredimensioned to correspond with the gap portions 30 and 32 of the outerrim 28. The corresponding projections of the upper support holder 60 aidin the proper seating and assembly of the ring assembly 10 by ensuringthat the gap portions and projections are mated correctly in an abuttingrelationship. If the upper and lower support holders 20 and 60 are notproperly fitted together, they will not properly align, and the assemblywould not be able to be assembled in the relationship illustrated inFigure 1.

[0040] Desirably, as shown in FIG. 1, the bore of the upper supportholder 60 is provided with depending projections 80 adapted to supportthe cutting member 130. Depending support 80 include correspondingsupport projections 82 adapted to aid in supporting the support ringcutting or tear initiation points 110. Depending support 80 includesarcuately curved sections 84 adapted to reinforce or support arcuatelycurved members 134. The depending support 80, aids in supporting thecutting member 130 when the predetermined burst pressure of a reverserupture disc has been exceeded and the disc reverses and is cut open onthe tear initiating members 110 and the cutting edge 130. Typically,this pressure is substantial and the bursting of the disc 50 is quiterapid and places pressure upon the support ring cutting member. As suchit is desirable to support the cutting pattern in such a way thatsubstantially all of the cutting surfaces are supported againstundesirable bending or twisting during the serration or cutting of thedisc 50. Most preferably the projections have the substantially similartransition radius and transition diameter to that of the support ringand rupture disc. By having the innermost segments of the contouredconfigurations coincide with the defined bore of the upper supportholder, the present invention enables a bursting disk to be applicablefor both gas and liquid applications and for high and low pressureapplications.

[0041] In use, the assembly 10 is clamped in a pressure line (notshown). The lower support holder or flange 20 is placed toward thepressure flow, followed in an abutting and sealed sequentialrelationship, a reverse buckling disc 50, a support ring 100 and anupper support holder or flange 60, positioned such that any pressuremust first contact the disc 50. When pressure in the vessel is greaterthan the rupture pressure of the rupture disc 50, the disc reverse discpressure load is exceeded and upon rupture, the pressure is relievedthrough the assembly 110.

[0042] As the reverse buckling disc 50 reverses upon itself, the dome orconcave convex portion of the disc is forced against the cutting edgepattern 130 of the support ring 110. The cutting pattern 130 effectivelycuts the disc 50 along the continuous cutting edge such that the cutawayportion of the disc folds or hinges along the projection member 120.

[0043] In a further alternative embodiment, the upper support holder orflange 60 includes a depending projection, having a substantiallysimilar configuration to that of the cutting pattern of the support ring110. This depending projection provides for additional support of thecutting member 130 during the bursting of the disc 50.

[0044] Desirably, a method for forming the support ring includesproviding a blank for use as a support ring is manufactured throughconventional means, ie pressing, cutting etc., resulting in a bulged outor domed shape configuration. Ideally, once formed, the disc 50 includesa flange portion, and a concave/convex dome, and a pre-determinedtransition region having a transition radius and transition diametersubstantially equal to that of a corresponding disc member. Asunderstood, the term transition radius used herein is used to describethe area between the flange portion of the disc and the dome portion ofthe disc having a predetermined radius and angle. The transitiondiameter is understood to describe the length of the area between theflange sides.

[0045] In a preferred embodiment, the transition diameter of the supportring 110 has a predetermined length alpha, which is substantiallysimilar to that of the of the transition diameter beta of the disc 50.The substantially similar transition diameters provide for a closer ormore snug fit between the disc 50 and the support ring 110 which allowsfor less movement of the disc upon burst and aids in the efficientcutting of the disc 50 upon the tear initiation points or cutting points132 and arcuate cutting members 134.

[0046] A preferred method of forming the cutting pattern 130 of thesupport ring 110 is utilizing a precision cutting means, such as alaser, to effectively cut or otherwise form the clover leaf cuttingpattern 130 in the pre-formed blank. This provides for a more precisecutting of the support ring surface, as the laser optimally cuts at a 90degree angle to the ring surface. The laser provides (or forms) acutting edge having a predetermined angle extending for at least a majorportion of the pattern. As stated, the cutting edge has a predeterminedangle of between 50 and 70 degrees, and most preferably has a cuttingangle of approximately 60 degrees.

[0047] Although embodiments of the invention have been described above,it is not limited thereto and it will be apparent to those skilled inthe art that numerous modifications form part of the present inventioninsofar as they do not depart from the spirit, nature and scope of theclaimed and described invention.

I claim:
 1. In a rupture disc assembly having a support ring adapted tosupport a rupturable rupture disc member; said support ring including anaperture, spaced upper and lower surfaces, a continuous side surface andat least one tear-initiation projection, the improvement wherein saidsupport ring includes contiguous cutting means about said, aperture,said cutting means comprising a plurality of arcuately contouredsegments having an innermost arc portion and caution of the arcuatesegments spaced closer to said inner peripheral wall than the otherportions of the arcuate segments.
 2. A rupture disc support ringcomprising: a substantially flat support ring having a pair of opposedplanar surfaces and a central aperture extending between said surfacesencircled by said ring; at least one tear-initiation projection forinitiating a tear in a reverse buckling disc, said projection extendingfrom said planar support ring inwardly into said aperture and projectingdownwardly and below one of said opposed surfaces; and arcuatelycontoured cutting means at least partially surrounding said aperture andextending either side of said tear-initiation projection, said cuttingmeans having an innermost segment of the arcuately contoured cuttingmeans abutting said support ring and projecting downwardly from said oneof said opposed surfaces.
 3. The apparatus of claim 1 , wherein saidsupport ring includes means to prevent fragmentation of a reversebuckling disc when said disc is ruptured.
 4. The apparatus of claim 3 ,wherein said means comprises an inwardly extending tab associated withsaid support ring.
 5. The apparatus of any one of claim 1 , wherein saidsupport ring is in combination with a reverse buckling rupture disc,said rupture disc comprising a dome-shaped central member surrounded bya substantially planar annular flange, said rupture disc having atransition radius between said flange and said dome-shaped member. 6.The apparatus of claim 5 , wherein said support ring includes atransition radius between one of said planar surfaces and the downwardlyand inwardly extending tear initiation projection, said transitionradius of said support ring being substantially the same as thetransition radius of said reverse buckling rupture disc.
 7. Theapparatus of claim 5 , wherein said support ring includes a transitiondiameter between one of said planar surfaces and the downwardly andinwardly extending tear initiation projection, said transition diameterof said support ring being substantially the same as the transitiondiameter of said reverse buckling rupture disc.
 8. The apparatus ofclaim 4 , said apparatus including cooperating first and second holdingmeans for mounting said support ring and said reverse buckling rupturedisc, said first and second holding means having a central aperture, andmeans for retaining said first and second holding means within operativerelationship with said support ring and said rupture disc.
 9. Theapparatus of claim 8 , wherein one of said holding means includes anaperture having a configuration corresponding substantially to theaperture configuration of said support ring.
 10. The apparatus of claim9 , wherein said holding means includes a plurality of support means forsupporting said plurality of spaced-apart tear initiation projection ofsaid support ring.
 11. The apparatus of claim 10 , wherein said holdingmeans has a plurality of arcuately contoured sides of said apertureextending between opposed surfaces of said holding means, said arcuatelycontoured sides corresponding in shape to the arcuately contouredconfiguration of said cutting means of said support ring.
 12. Theapparatus of any one of claim 6 , wherein at least one of said holdingmeans includes positioning means for positioning said support ring in apredetermined direction between said holding means.
 13. The apparatus ofclaim 12 , wherein said positioning means comprises a projectionextending from one of said holding means, the other of said holdingmeans having a recess adapted to receive said projection, and saidsupport ring having means for receiving said projection and positioningsaid support ring between said holding means.
 14. For use with an upperholding member having a bore and a lower annular surface; a rupture discand support member assembly comprising a rupture disc having an annularperipheral section and a domed central section extending downwardly fromsaid upper holding member, and a support member having an annularperipheral section resting on said annular peripheral section of saidrupture disk and at least one cutting projection extending downwardlyfrom said peripheral section, in close proximity to said domed sectionfor initiating tear in said domed section, and arcuately contouredcutting edges extending each side of said cutting projection, saidcutting edges each including an inner arc section coincidental with saidupper holding member when said upper holding member is positioned on anupper surface of said peripheral section of said support member.
 15. Anassembly as claimed in claim 14 , including a plurality of spacedcutting projections.
 16. An assembly as claimed in claim 14 , includinga cord section on an inner periphery at the annular peripheral sectionof the support member, said cord section forming a hinge member.
 17. Abursting disc assembly including a reverse buckling bursting disccomprising: a lower tubular holding member having a bore and spacedapart annular seating surfaces, an upper surface and a lower surface; areverse buckling bursting disc having a peripheral annular sectionseated on the upper surface of the lower holding member and a domedcentral section extending down into the bore of the lower holdingmember; a support member having a peripheral annular section seated onsaid annular section of the bursting disc and at least one tearinitiating member extending downwardly within said domed portion and inclose proximity thereto, and arcuately contoured cutting edges extendingon each side of the said tear initiating member; an upper tubularholding member having a bore and spaced apart annular seating surfaces,an upper surface and a lower surface, the lower surface seated on saidperipheral annular section of said support member; and said contouredcutting edges including innermost arc sections coinciding with the boreof the upper holding member.
 18. An assembly as claimed in claim 17 ,including a plurality of space tear initiating members.
 19. An assemblyas claimed in claim 17 , including a chord section, on an innerperiphery of the annular peripheral section of the support member, saidchord section forming a hinge member.
 20. An assembly as claimed inclaim 17 , including support formations extending down from said upperholding member to support said tear initiating member or members.